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DOUBLE PRECISION FUNCTION D1MACH(I)
INTEGER I
C
C DOUBLE-PRECISION MACHINE CONSTANTS
C D1MACH( 1) = B**(EMIN-1), THE SMALLEST POSITIVE MAGNITUDE.
C D1MACH( 2) = B**EMAX*(1 - B**(-T)), THE LARGEST MAGNITUDE.
C D1MACH( 3) = B**(-T), THE SMALLEST RELATIVE SPACING.
C D1MACH( 4) = B**(1-T), THE LARGEST RELATIVE SPACING.
C D1MACH( 5) = LOG10(B)
C
INTEGER SMALL(2)
INTEGER LARGE(2)
INTEGER RIGHT(2)
INTEGER DIVER(2)
INTEGER LOG10(2)
INTEGER SC, CRAY1(38), J
COMMON /D9MACH/ CRAY1
SAVE SMALL, LARGE, RIGHT, DIVER, LOG10, SC
DOUBLE PRECISION DMACH(5)
EQUIVALENCE (DMACH(1),SMALL(1))
EQUIVALENCE (DMACH(2),LARGE(1))
EQUIVALENCE (DMACH(3),RIGHT(1))
EQUIVALENCE (DMACH(4),DIVER(1))
EQUIVALENCE (DMACH(5),LOG10(1))
C THIS VERSION ADAPTS AUTOMATICALLY TO MOST CURRENT MACHINES.
C R1MACH CAN HANDLE AUTO-DOUBLE COMPILING, BUT THIS VERSION OF
C D1MACH DOES NOT, BECAUSE WE DO NOT HAVE QUAD CONSTANTS FOR
C MANY MACHINES YET.
C TO COMPILE ON OLDER MACHINES, ADD A C IN COLUMN 1
C ON THE NEXT LINE
DATA SC/0/
C AND REMOVE THE C FROM COLUMN 1 IN ONE OF THE SECTIONS BELOW.
C CONSTANTS FOR EVEN OLDER MACHINES CAN BE OBTAINED BY
C mail netlib@research.bell-labs.com
C send old1mach from blas
C PLEASE SEND CORRECTIONS TO dmg OR ehg@bell-labs.com.
C
C MACHINE CONSTANTS FOR THE HONEYWELL DPS 8/70 SERIES.
C DATA SMALL(1),SMALL(2) / O402400000000, O000000000000 /
C DATA LARGE(1),LARGE(2) / O376777777777, O777777777777 /
C DATA RIGHT(1),RIGHT(2) / O604400000000, O000000000000 /
C DATA DIVER(1),DIVER(2) / O606400000000, O000000000000 /
C DATA LOG10(1),LOG10(2) / O776464202324, O117571775714 /, SC/987/
C
C MACHINE CONSTANTS FOR PDP-11 FORTRANS SUPPORTING
C 32-BIT INTEGERS.
C DATA SMALL(1),SMALL(2) / 8388608, 0 /
C DATA LARGE(1),LARGE(2) / 2147483647, -1 /
C DATA RIGHT(1),RIGHT(2) / 612368384, 0 /
C DATA DIVER(1),DIVER(2) / 620756992, 0 /
C DATA LOG10(1),LOG10(2) / 1067065498, -2063872008 /, SC/987/
C
C MACHINE CONSTANTS FOR THE UNIVAC 1100 SERIES.
C DATA SMALL(1),SMALL(2) / O000040000000, O000000000000 /
C DATA LARGE(1),LARGE(2) / O377777777777, O777777777777 /
C DATA RIGHT(1),RIGHT(2) / O170540000000, O000000000000 /
C DATA DIVER(1),DIVER(2) / O170640000000, O000000000000 /
C DATA LOG10(1),LOG10(2) / O177746420232, O411757177572 /, SC/987/
C
C ON FIRST CALL, IF NO DATA UNCOMMENTED, TEST MACHINE TYPES.
IF (SC .NE. 987) THEN
DMACH(1) = 1.D13
IF ( SMALL(1) .EQ. 1117925532
* .AND. SMALL(2) .EQ. -448790528) THEN
* *** IEEE BIG ENDIAN ***
SMALL(1) = 1048576
SMALL(2) = 0
LARGE(1) = 2146435071
LARGE(2) = -1
RIGHT(1) = 1017118720
RIGHT(2) = 0
DIVER(1) = 1018167296
DIVER(2) = 0
LOG10(1) = 1070810131
LOG10(2) = 1352628735
ELSE IF ( SMALL(2) .EQ. 1117925532
* .AND. SMALL(1) .EQ. -448790528) THEN
* *** IEEE LITTLE ENDIAN ***
SMALL(2) = 1048576
SMALL(1) = 0
LARGE(2) = 2146435071
LARGE(1) = -1
RIGHT(2) = 1017118720
RIGHT(1) = 0
DIVER(2) = 1018167296
DIVER(1) = 0
LOG10(2) = 1070810131
LOG10(1) = 1352628735
ELSE IF ( SMALL(1) .EQ. -2065213935
* .AND. SMALL(2) .EQ. 10752) THEN
* *** VAX WITH D_FLOATING ***
SMALL(1) = 128
SMALL(2) = 0
LARGE(1) = -32769
LARGE(2) = -1
RIGHT(1) = 9344
RIGHT(2) = 0
DIVER(1) = 9472
DIVER(2) = 0
LOG10(1) = 546979738
LOG10(2) = -805796613
ELSE IF ( SMALL(1) .EQ. 1267827943
* .AND. SMALL(2) .EQ. 704643072) THEN
* *** IBM MAINFRAME ***
SMALL(1) = 1048576
SMALL(2) = 0
LARGE(1) = 2147483647
LARGE(2) = -1
RIGHT(1) = 856686592
RIGHT(2) = 0
DIVER(1) = 873463808
DIVER(2) = 0
LOG10(1) = 1091781651
LOG10(2) = 1352628735
ELSE IF ( SMALL(1) .EQ. 1120022684
* .AND. SMALL(2) .EQ. -448790528) THEN
* *** CONVEX C-1 ***
SMALL(1) = 1048576
SMALL(2) = 0
LARGE(1) = 2147483647
LARGE(2) = -1
RIGHT(1) = 1019215872
RIGHT(2) = 0
DIVER(1) = 1020264448
DIVER(2) = 0
LOG10(1) = 1072907283
LOG10(2) = 1352628735
ELSE IF ( SMALL(1) .EQ. 815547074
* .AND. SMALL(2) .EQ. 58688) THEN
* *** VAX G-FLOATING ***
SMALL(1) = 16
SMALL(2) = 0
LARGE(1) = -32769
LARGE(2) = -1
RIGHT(1) = 15552
RIGHT(2) = 0
DIVER(1) = 15568
DIVER(2) = 0
LOG10(1) = 1142112243
LOG10(2) = 2046775455
ELSE
DMACH(2) = 1.D27 + 1
DMACH(3) = 1.D27
LARGE(2) = LARGE(2) - RIGHT(2)
IF (LARGE(2) .EQ. 64 .AND. SMALL(2) .EQ. 0) THEN
CRAY1(1) = 67291416
DO 10 J = 1, 20
CRAY1(J+1) = CRAY1(J) + CRAY1(J)
10 CONTINUE
CRAY1(22) = CRAY1(21) + 321322
DO 20 J = 22, 37
CRAY1(J+1) = CRAY1(J) + CRAY1(J)
20 CONTINUE
IF (CRAY1(38) .EQ. SMALL(1)) THEN
* *** CRAY ***
CALL I1MCRY(SMALL(1), J, 8285, 8388608, 0)
SMALL(2) = 0
CALL I1MCRY(LARGE(1), J, 24574, 16777215, 16777215)
CALL I1MCRY(LARGE(2), J, 0, 16777215, 16777214)
CALL I1MCRY(RIGHT(1), J, 16291, 8388608, 0)
RIGHT(2) = 0
CALL I1MCRY(DIVER(1), J, 16292, 8388608, 0)
DIVER(2) = 0
CALL I1MCRY(LOG10(1), J, 16383, 10100890, 8715215)
CALL I1MCRY(LOG10(2), J, 0, 16226447, 9001388)
ELSE
WRITE(*,9000)
STOP 779
END IF
ELSE
WRITE(*,9000)
STOP 779
END IF
END IF
SC = 987
END IF
* SANITY CHECK
IF (DMACH(4) .GE. 1.0D0) STOP 778
IF (I .LT. 1 .OR. I .GT. 5) THEN
WRITE(*,*) 'D1MACH(I): I =',I,' is out of bounds.'
STOP
END IF
D1MACH = DMACH(I)
RETURN
9000 FORMAT(/' Adjust D1MACH by uncommenting data statements'/
*' appropriate for your machine.')
* /* Standard C source for D1MACH -- remove the * in column 1 */
*#include <stdio.h>
*#include <float.h>
*#include <math.h>
*double d1mach_(long *i)
*{
* switch(*i){
* case 1: return DBL_MIN;
* case 2: return DBL_MAX;
* case 3: return DBL_EPSILON/FLT_RADIX;
* case 4: return DBL_EPSILON;
* case 5: return log10(FLT_RADIX);
* }
* fprintf(stderr, "invalid argument: d1mach(%ld)\n", *i);
* exit(1); return 0; /* some compilers demand return values */
*}
END
SUBROUTINE I1MCRY(A, A1, B, C, D)
**** SPECIAL COMPUTATION FOR OLD CRAY MACHINES ****
INTEGER A, A1, B, C, D
A1 = 16777216*B + C
A = 16777216*A1 + D
END
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